1. Field of the Invention
The invention relates to a high-quality ink jet recording medium. Specifically, the invention relates to an ink jet recording medium that provides a ink jet print having a sharpness and a sense of depth and is excellent in recordings of images of people or the like.
2. Description of the Related Art
Recently, various information processing systems have been developed along with rapid development in the information industry. Recording methods and devices suitable for these information processing systems have also been developed and variously put to practical use.
Examples of practically used recording methods include, in addition to silver salt photographic methods, electrophotographic methods, ink jet recording methods, thermal recording methods, sublimation transfer methods and thermal transfer methods. The requirement to obtain sharp and vividly hued high-resolution images is the same in any of the above-mentioned recording methods.
Among the above-mentioned recording methods, the ink jet recording method can be used to record on many kinds of recording materials, and hardware (a device) therefor is comparatively low-priced, compact, and very quiet. Therefore, the ink jet recording method has been widely used in the office as well as at home.
Further, various mediums for ink jet recording have been developed in recent years along with the achievement of high resolution ink jet printers and the development of hardware (devices), and it has become possible to obtain so-called “photograph-like” high-quality recorded products.
In particular, examples of the properties required for the mediums for ink jet recording include (1) quick drying (high ink absorption speed), (2) ink dots having proper and uniform diameters (no bleeding), (3) excellent granularity, (4) high circularity of dots, (5) high color density, (6) high saturation (no dullness), (7) excellent light fastness, gas resistance and water resistance at printed portions, (8) a recording surface having a high degree of whiteness, (9) excellent storability of a recording medium (no yellow discoloration or image bleeding during long term storage), (10) resistance to deformation and excellent dimensional stability (sufficiently small curl), and (11) excellent running properties in hardware. Further, in addition to the above-mentioned properties, glossiness, surface flatness and texture similar to that of a silver salt photograph are required for use as photographic glossy paper used to obtain the photograph-like high-quality recorded product.
A specific example is an ink jet recording sheet containing fine inorganic pigment particles and a water soluble resin, wherein the recording sheet has a porous coloring material receiving layer with a high void ratio is provided on a support (for example, see Japanese Patent Application Laid-Open (JP-A) Nos. 10-119423 and 10-217601). These sheets, in particular an ink jet recording sheet comprising a coloring material receiving layer composed of a porous structure using silica as the inorganic pigment fine particles is excellent in ink-absorbability due to its structure, while the sheet also has a high ink-receiving performance that enables high resolution images to be formed with high luster.
Although a photograph-like image may be obtained by giving the recording sheet a glossy finish, this glossiness varies with the image shape and the glossiness easily becomes uneven. When such an uneven difference in glossiness of image shapes is generated, glare is generated on the image surface, causing an unnatural print, and the print is not one which provides a sense of high quality. In order to eliminate the differences in glossiness of image shapes, a method has been disclosed which regulates and improves glossiness in which center line average (CLA) roughness average (Ra) of the surface of the ink-receiving layer is increased to 0.8 to 4.0 μm (for example, see Japanese Patent Laid-Open No. 2000-355160). Generally, an improvement in image quality requires not only a sense of glossiness, but also photograph-like stereoscopic expression providing a sense of depth, brilliant vividness, and sharpness providing a sense of clarity.
However, the aforementioned methods have a poor ability to depict the shine in the eyes or clearly show the hair, or give a sense of depth in portrait images or the like, and it is currently difficult to say these methods are suitable for recording images of people and the like.